1. Field of the Invention
This invention relates in general to hydroconversion and more particularly to a method of hydroconversion of solid carbonaceous materials.
2. Description of the Prior Art
Due to the shortage of liquified hydrocarbon fuels and related chemicals, research in the area of hydroconversion of solid carbonaceous material has increased in an effort to produce these fuels and chemicals. However, most of the fundamental chemistry involved in hydroconversion of carbonaceous material has been known for some time. Nevertheless, new processes for coal liquefaction and coal gasification are constantly being invented to provide advantageous new methods of utilizing the known chemistry. A representative sampling of some of the inventions are shown in U.S. Pat. Nos. 3,856,675; 3,852,183; 3,852,182; 3,790,467; 3,607,719; 3,594,303; 3,540,995; 3,514,394; and Re. 25,770.
A particular problem of the prior art has been that the equipment required for hydroconversion of coal or the like has been very expensive. One reason for this expense has been the necessity of using only very high temperatures and pressures. In fact, many inventions have been devoted to coping with these high temperatures and pressures.
Another problem of the prior art is also due, in part, to the high pressures and temperatures used in these processes. This problem involves the addition of hydrogen to a hydroconversion process. In the past, hydrogen has been usually added to systems for hydrogenation under very high pressure. Furthermore, more hydrogen than necessary for hydrogenation has been added because the excess hydrogen increases the rate of hydrogenation. This excess hydrogen requires a larger gas compressor than necessary and leads to larger and more complex hydrogen purification and recycle system components. Since gas compressors and hydrogen purification and recycle system components are expensive and inefficient, the use of this excess hydrogen results in high costs.
Still another problem in the prior art has been the removal of finely dispersed minerals and metals (ash) during the hydroconversion process. In the past, these solids have been removed in processes which either are unreliable due to plugging or are inefficient due to loss of feed and product materials during separation from the hydrocarbons. The ash has usually been removed at the beginning of the hydroconversion processes to prevent plugging of catalyst beds, to reduce erosion in components, and to ensure products have low ash content.